航空材料学报

Effects of the elevated temperatures on the low cycle behavior of zircaloy-4

CAI Li-xun, FAN Xuan-hua, LI Cong, QIU Shao-yu

2004, 24(5): 1-6.

[Abstract](1402) [PDF 499KB](359)

Abstract:
A series of tests of bugle-flat specimens on the LCF ( Low Cycle Fatigue) behavior of Zircaloy-4 at room and 400℃ were investigated. Manson-Coffin(M-C) life estimation models and Ramberg-Osgood(R-O) monotonic constitutive models at room and 400℃ temperatures are given respectively. Systematical investigations about the influences of the elevated temperature on monotonic tensional intensity, cyclic intensity and fatigue life of Zircaloy-4 were performed by three temperature factors of the alloy related to the elevated temperature. According to acknowledge that it exists a linearity relationship between life temperature factor and strain amplitude, a modified M-C model for predicting the fatigue life at elevated temperature was proposed. In addition, the temperature effects of Zircaloy-4 on stress amplitude at 200~400℃ were discussed.

Research on shape memory effects in Cu-Zn-Al alloys by (SIM+SME) training method

HUANG Wan-xia, SONG Zhi-min

2004, 24(5): 7-10,14.

[Abstract](1459) [PDF 510KB](216)

Abstract:
Shape memory effects on Cu-Zn-Al alloys trained with(SIM + SME) shape memory training method have been investigated. The resuhes show that one-way shape memory effect η0 firstly decreases rapidly, then slowly and finally keeps stable with the increasing of the training cycle where a large amount of dislocation slip movement and dislocation are produced. The η0 arriving at stable is less than the 50% of original η0 However the two-way shape memory effect ηT firstly increases rapidly to a peak value at training cycle10, then decreases slowly and finally keeps stable. The ηT up to 64%~88% of peak value. In the same time,shape memory sensitivity deteriorates after(SIM + SME) training. The shape memory sensitivity at stability declines the 58% of original value. The deteriorationes of shape memory effect and shape memory sensitivity after training should be paid great attention during designing of shape memory device.

Research of structure and properties of alloy bar 25Cr3MoA for aeroengine

CHI Xiu-bin, ZOU Tian-lai, CHEN Si-lian, LIU Chun-ming

2004, 24(5): 11-14.

[Abstract](1476) [PDF 800KB](199)

Abstract:
Effect of heat treatment on structure and properties of steel 25Cr3MoA has been studied. The results shows that the structure of steel 25Cr3MoA remehed by electroslag process was homogeneous. Low temperature impact toughness after by process WS9-6001 was better than those of other groups. There was no way to convert Aki into Akv.

Study of heat treatment processings of TC6 titanium alloy bars

ZHU Zhi-shou, WANG Qing-ru, ZHOU Yu, WANG Xin-nan

2004, 24(5): 15-20.

[Abstract](1449) [PDF 657KB](223)

Abstract:
A stady of the heat treatment of TC6 Titanium alloy bars have been conducted. The bars of the alloy with the diameter ranging from 20mm to 120mm have undergone the conventional annealing, dual annealing, and isothermal annealing and the relationships among heat treatment, microstructure and property have been analyzed. The result shows that the microstrueture and properties of TC6 Titanium alloy are sensitive to its heat treatment processing and thus the optimum heat treatment method should be chosen to achieve to the perfect combination of strength, plasticity, and toughness according to the specification, type, shape of cross section, operating temperature, condition of stress of semi-products and equipments available. It is proved that conventional annealing is a feasible way for the annealing of seml-products used in aircraft structure, such as bars et al. The principles for the selection of heat treatment methods of TC6 Titanium alloy bars are also presented for reference of research and manufacture.

Modeling and validation for spike-like weld profile in electron beam welding of nickel-based superalloy

ZHANG Hai-quan, ZHANG Yan-hua, ZHAO Hai-yan, ZHANG Xing-an

2004, 24(5): 21-25.

[Abstract](1560) [PDF 768KB](462)

Abstract:
According to the spike-liked weld profile in electron beam welding, a penetration model of the combination of moving Gauss area heat source and moving cylindrical volume heat source is presented, which based on the effects of energy absorption and redistribution in the melt pool and keyhole. The three-dimensional temperature fields for both the full penetration mode and partial penetration mode in EBW of GH4133 superalloy are performed using a commercial FEM code, ANSYS. Experimental studies of metallurgic graph have also been conducted to validate the numerical models presented. It has been shown that the FE analysis predicted deep penetration weld shape is found to be in fair agreement with the corresponding experimental. It would be possible to provide a reliable solution for the further analysis on multiphysical coupled field such as thermal, mechanical and microstrueture.

Microstructures and mechanical properties of carbon fiber reinforced silicon oxycarbide composites fabricated via hot-pressing assisted pyrolysis of polysiloxane

MA Qing-song, CHEN Zhao-hui, ZHENG Wen-wei, HU Hai-feng

2004, 24(5): 26-30.

[Abstract](1473) [PDF 775KB](186)

Abstract:
Three-dimensional braided carbon fiber reinforced silicon oxycarbide composites(3DB Cf/Si—O—C) were fabricated via polysiloxane infiltration and pyrolysis. It was found that the density and mechanical properties of 3D-B Cf/ Si—O—C could be increased remarkably if the first pyrolysis was assisted by hot-pressing. When the first pyrolysis was carried out at 1600℃ for 5min with a pressure of 10MPa, the flexural strength and fracture toughness of the resultant 3D-B Cf/ Si—O—C were increased from 246.2MPa and 9.4MPa·m1/2 to 502MPa and 23.7MPa·m1/2, which was attributed to the desirable interracial bonding, increased in-situ strength and density as the results of high temperature and pressure. In high temperature flexural tests, the strength of the composite at room temperature was maintained to 1400℃ under vacuum.

Cured behavior and microscopic configuration of phenolic resin modified by polyathylene-vinyl alcohol

WANG Chao, HUANG Yu-dong, XüXiao-mu

2004, 24(5): 31-34.

[Abstract](1460) [PDF 461KB](425)

Abstract:
In this paper, thermosetting phenolic resin modified by polyathylene-vinyl alcohol which can dissolve in phenol water was prepared. And its cured character and microscopic configuration were researched with IR,DSC,TG,SEM and TEM spectra. During curing process, hydroxy group of polythylene-vinyl alcohol was condensed with hydroxymethod of phenolic resin into intersectional structure, which was good at heat-resistance and toughness. And the analysis conclusion of SEM and TEM spectra were correspondence with that of IR, DSC,TG spectra analysis.

On the interfacial debonding of particulate-reinforced nonlinear viscoelastic polymeric material

CHANG Liu-hong, CHEN Jian-kang, BAI Shu-lin

2004, 24(5): 35-39.

[Abstract](1461) [PDF 429KB](177)

Abstract:
The interfacial debonding of particulate-reinforced polymeric material is studied in this paper. Firstly, a nonlinear viscoelastic model is proposed to describe the constitutive relation of the polymeric matrix. Then the interfacial debonding of a particle embedded polymeric matrix material is analyzed, and the equation for solving the critical debonding time is derived. The expression of the debonding time under the condition of linear loading history is obtained from the equation. Finally, the numerical calculation is carried out, and the numerical results indicate that the debonding time is significantly influenced by the particle size, loading rate, interfacial adhesive energy and nonlinear viscosity parameter.

Influence of barium titanate on the damping properties of interpenetrating polymer networks based nanocomposites

TANG Dong-yan, LIU Li-li, ZHANG Ju-sheng, JIN Zheng, ZHAO Lian-cheng

2004, 24(5): 40-43.

[Abstract](1460) [PDF 479KB](274)

Abstract:
Well-dispersed BaTiO3/IPNs damping nanocomposites based on modified polyurethane(PU) and unsaturated polyester resin (UP) interpenetrating polymer networks were prepared by in-situ polymerization process and using BaTiO3 nano powders and fibers as filler. The influences of shapes and amounts of BaTiO3 in system on damping behaviors were studied. The results indicated that, the damping properties of the composites were affected mainly by the shapes of filler besides the kinds of that added. Fiber-shaped BaTiO3 increased the values of loss factor(tanδ) and the peak areas of loss modulus(E") apparently. As the amount of BaTiO3 added into the system increased to 70%(V/V), E"improved 102 times compared with that of pure PU/UP IPNs, and both the shoulder peak and main transitional peak moved toward relative higher temperature ranges. So the values of loss factors at room temperature could been enlarged greatly by the adding of BaTiO3.

Study on rudder clamping method of paper honeycomb

LIU Gang, KE Ying-lin

2004, 24(5): 44-48,52.

[Abstract](1212) [PDF 1134KB](178)

Abstract:
Rudder part was studied as an example using the new clamping method based on the magnetic field and friction-clamping principle. The element forming of region segmentation and the relationship between Z direction deformation and honeycomb height were analyzed under the certain high - speed milling condition. With regard to the rudder part, a special structure design for clamping device was fulfilled based on experiment testing and finite element analyzing. As the result, clamping position and the reaction force of the position were determined and the structure function was given in detail.

Rheological behavior of aqueous Al₂O₃ slurries with talc

LI Bao-wei, CHEN Da-ming, TONG Jian-feng, LIU Xiao-guang

2004, 24(5): 49-52.

[Abstract](1471) [PDF 483KB](220)

Abstract:
The effect of talc on the rheological behavior of Al2O3 slurries was studied. When the content of talc was less than 4wt% , the viscosity of Al2O3 slurry increased slightly with an increase in talc content. Comparing with the Al2O3 slurry without talc, the Al2O3 slurry with talc was of distinct thixotropy. For the Al2O3 slurry with 0.5wt% talc and 55wt% solid content, the highest fluidity was gained when the milling time was 16~18h.

Elastic-plastic fatigue crack propagation under combined torsion and tension

YU Hui-chen, XIE Shi-shu, SUN Yan-guo, TANAKA Keisuke

2004, 24(5): 53-56,62.

[Abstract](1200) [PDF 391KB](236)

Abstract:
Fatigue crack propagation tests were conducted on a circumferentially pre-cracked round bar of a medium carbon steel under combined torsion and tension. The fatigue fracture surface was macroscopically flat under the conditions of excessive plasticity and the crack propagation rate were expressed as a power function of J integral range for both single and mixed mode. For the same J integral range, the mode Ⅰ propagation rate was the highest and the mode Ⅲ one was the lowest. Striations were observed on the fatigue fracture surface made under mixed mode loading, and their spacing was equal to the crack propagation rate, the same as mode Ⅰ case.

An application of subjective speckle technique for microcosmic observation of evolvement of stress corrosion of aluminum alloy

SHI Hui-ji, RUAN Chun-yi, LI Xi-de

2004, 24(5): 57-62.

[Abstract](1433) [PDF 1411KB](211)

Abstract:
An optical system has been set up to observe the initial process of stress corrosion, the application of the subjective speckle technique in observation of stress corrosion has been introduced. This method combined scatter and statistical speckle techniques; through computing the microstructure changes of roughness caused by stress corrosion studied initial process of stress corrosion. This method is applied in stress corrosion initial evolvement experiment of aluminum alloy Al2024-T3 board in 3.5% sodium chloride solution. the results showed that this method is sensitive enough for measurement of roughness, computing the average intensity of spackle-patterns is a easy and effectual method for studying the influence of each condition to the initial process of stress corrosion.

2004 Vol. 24, No. 5